fix(docs): typos in installation.md regarding Qt backend

[strniko]

Fixes Issue

Spelling errors in the installation manual

Description

A bunch of minor spelling mistakes, no major changes

Check List

Check all the applicable boxes:

• I understand that my contributions needs to pass the checks;
• If I created new functions / methods, I documented them and add type hints;
• If I modified already existing code, I updated the documentation accordingly;
• The title of my pull request is a short description of the requested changes.

Note to reviewers

This is a minor cosmetic change

[jeertmans]

Thank you very much @strniko! Could you add an entry in the CHANGELOG.md file to document your contribution?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.09%. Comparing base (0b36f79) to head (56a6112).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #580   +/-   ##
=======================================
  Coverage   79.09%   79.09%           
=======================================
  Files          23       23           
  Lines        2038     2038           
=======================================
  Hits         1612     1612           
  Misses        426      426           

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[jeertmans]

Thanks you @strniko!